Ferrite Isolators/Circulators have a great deal of applicability in microwave applications. While the design and function of the ferrite isolator/circulator has proven to be reliable and repeatable, the device structure and contacts for connecting the ferrite isolator/circulator to signal transmission lines has proven to have problems from the standpoint of manufacturing and/or ease of installation and subsequent progression into automation. To this end, the conventional structure for a ferrite isolator/circulator is shown in cross section in FIGS. 1a and 1b. The structure shown in FIG. 1a is a typical ferrite housing can 101 with the ferrite isolator/circulator mounted therein having electrical connections for surface mount application such as lead 102 as shown in FIGS. 1a and 1b. The top view of the ferrite can is shown in FIG. 1c with the leads 102 shown for typical applications. Surface mount technology in the microwave industry has wide spread applicability and acceptance. Structures such as shown in FIGS. 1a-1c are designed to be adaptable to surface mount technology. The lead assembly shown in FIG. 1b has the lead 102 designed to rest in the same plane as the bottom of the can as at 103. The purpose of this is to ensure good electrical connection and also ensure that the main housing base has a good electrical contact with its respective contact surface on the PC Board. Although, zero tolerance coplanarity would be ideal, common manufacturing practices allow a certain amount of tolerance of deviation, but more tolerance than would be allowed by typical solder pad thickness deposition from the ferrite to the signal line via lead 102. Thereafter, the lead 102 is soldered via a solder pad to the signal transmission line disposed on the printed circuit board.
While the design shown in FIGS. 1a-1c has met with some success, there are certain drawbacks which have proven problematic with this design. As stated, the industry standard is the use of surface mount technology. Unfortunately, the structure shown in FIGS. 1a-1c requires manual placement of the ferrite cans and contacts as opposed to a automated pick and place method of manufacture due to the lack of coplanarity of the contact leads relative to the base of the housing. Accordingly this slows down the process of manufacture and increases the labor intensity and therefore the overall cost. The reason that manual placement is required is to assure that the leads 102 are properly connected to the signal lines on the printed circuit board and done so in a reliable manner. One of the problems associated with the lead 102 is bending during handling and shipping of the device. The structure shown ideally in FIG. 1b has the lead 102 in the same plane as the bottom of the can at 103. During shipping and handling, the lead as shown can be bent and therefore not properly positioned. The assembly thereafter requires that the lead be rebent to its proper position. Even after the lead is properly bent and placed, there are reliability issues that require further testing time to assure electrical and mechanical integrity of the final product.
Accordingly, what is needed is a structure for ferrite isolator/circulator having a more robust and truly surface mount contact assembly which enables fully automated placement and soldering. Such a structure will enable a greater consistency from unit to unit and affect a more standard product.